Call distributing system



Jan. 12, 1932. J. F. DAHL CALL DISTRIBUTING SYSTEM A TTORNE V PM a S y a Jan. 12, 1932. J L 1,841,093

CALL DISTRIBUTING SYSTEM Filed March 18, 1931 11 Sheets-Sheet 2 E Q Q 3, o I

N lNVE/VTOR 6 J. F. 0/! H4 [f (Q-M A 7'TORNE Y Jan. 12, 1932. J, DAHL 1,841,093

CALL DISTRIBUTING SYSTEM Filed March 18, 1931 11 Sheets-Sheet 3 IN VENTOI? J. F. [M H/ A TTORNE Y Jan. 12, 1932. DAHL 1 ,841,093

CALL DISTRIBUTING SYSTEM Filed March 18, 1931 11 Sheets-Sheet 4 INVENTOR J. R. DA HL BY Rae/w- A TTORNEY Jan. 12, 1932. J F, DAHL 7 1,841,093

' CALL DISTRIBUTING SYSTEM Filed March 18, 1951 11 Sheets-Sheet 5 l lllill I lllll ll INVENTOR u J. F. DAHL E By 5 ATTORNEY Jan. 12, 1932.

J. F. DAHL CALL DISTRIBUTING SYSTEM Filed March 18, 1931 11 Sheet-Sheet 6 /NVEN7'OR J. F. DA HL A Z'TORNFV Jan. 12, 1932. J DAHL 1,841,093

CALL DISTRIBUTING SYSTEM Filed March 18, 1931 11 Sheets-Sheet 7 POLAR/ZED //v VENTOR J. F. DA HI.

FIG]

ATTORNEY Jan. 12, 1932. J. F. DAHL 1,841,093

CALL DISTRIBUTING SYSTEM Filed March 18, 1931 11 Shets-Sheet 8 E a U Q E q w VEN 70/? J. F. DAHL A TTORNE V Jan. 12, 191""02.v J, F, DAHL 1,841,093

CALL DISTRIBUTING SYSTEM I 18 1931 11 Sheet 1'. 9

}4unu m' iiiiiiii lllllll liiiiillllll INVENTOR J. F. DA HL FIG-9 ATTORNEY Jan. 12, 1932. DAHL 1,841,093

CALL DISTRIBUTING SYSTEM Filed March 18, 1951 1 sheets-sues; 10

' iiiiiijjl] INVENTOR J. RDA HL F/GJO A TT,ORNE Y- Jan. 12, 1932. J. F. DAHL 1,841,093

CALL DISTRIBUTING SYSTEM Filed March 18, 1951 11 Sheets-Sheet ll INVENTOR J. F. DA HL By $6.6M

A T'TORNEY brushes in each case. Tl'ierefore, each trunlr may have access to as many as one hundred thirty-two operators positions. lissociatet with each trunk is a lamp 172 and jack 170, located at the subscribers private branch exchange, which is distinct from and has a different designation than the order turret.

I The allotter circuit shown in Figs. 3 to T serves to dlrect'incomlng calls to storing circuits one at a time in a predetermined order. To insure continuity of service the allotter has been divided into two Si3l011$ I i P c 1 each oi which normally serves hair or tne incoming trunks, but is capable of serving of trunks may contain as many eleventrunks, but if less than the entire number 'of trunks is to be equipped thetrunks will be distributed over the groups and each group will contain less than the maximum number oftrunks. lVhenever a call is received on a trunk in one of the groups the corresponding group relay is operated. f Relays 521 to are cut-in relays and. operate in'response to the operation of the coresponding group re lay to give an indication to the storing cir cuit of the group within which the call originated, -Relays 531 to 536 are lock-out relavs and are used to prevent the handling or a second call in a particular group of trunks while a call is waiting in other groups. lays 621 and626 and 631 to 636 perform similar functions for the B ZLllOlJtQIZ The timing circuit of Fig. 7 serves to advance the switches 500 and 600 providedthey are not advanced by the storingcircuit within a predetermined length of time. It also operates an alarm if the advancing mechanism fails.

Fig. 8 represents one of twenty storing circuits by means of which calls incoming in rapid succession may be received and stored,

and subsequently directed to the attention of .an operator in the order 1n which they were stored. Two twenty-two position switches are employed to reach the one hundred thirty-two trunks since only two coiactor, in

'ter-connect thetrunk and the storing circult, whereby the twelve brushes may be. ar- 7 ranged in six groups of two brushes each,

each having access tov twenty-two trunks.

Relays 811, 812 and 813' in combination with relay 814 serve to identify, the particular switch andbru'sh set having'access to the group of trunks within which the calling trunklies. A group of twenty-two trunks to which a pair of brushes has access includes a corresponding group of eleven trunks from each allotter. v

The start circuit of Figs. 9 and 10 is also a duplicate arrangement for the purpose of insuring continuous service. thiscase the switches 900 and 1000 instead of operating simultaneously operate alternately, the arrival of one switch at its twentyfirst position serving to advance the other switch to its first position and the switches remaining on their twenty-second terminals when not in use. As in the case of the allotter circuit,.a plurality of timing relays are provided which serve to transfer all calls to one half of the start circuit when the other half fails for any reason. Each of the switches 900 and 1000 has access to the twenty storing circuits in the same order, and in the same order as the switches of the allotterh The allotter advances following the allotment of a call and may get well in advance of the start circuit, since the start clrcuit can only advance when one or H1016 order desks are free. However, since the allotter and start circuit advance over the storing circuits in the same order, the stored callsare directed to idle operators in the same order as that in whicn they were stored. V V

Each operator is provided as shown in Fig. 2 vith a receiving circuit 200. When the operator isa't her desk, she attaches her headset 220'to the position circuitby means ofplug 221 and jack 222 in the usual manner, operating relay'QQ l. Relay 2% in turn operates relay 203 which marks the desk available.

The desks of the order turret are ineftect divided into three groups by the provision of'the three switches individual to the trunk circuit In order to secure even distribution of calls over all three groups, the distribution control circuit of Fig. 11 prepares a circuit for causingthe operation of a particular switch in all trunks, which circuit is completed when the start circuit directs the trunk to start hunting. When the desk has been found, the switch 1100 in the distribution circuit is advanced to prepare the circuit for causingthe operation of a diflerent switch in all of the trunk circuits. v

An alarm circuit associated with the allotter has been omitted but is disclosed and described fully in the above identified Carpenter et al. patent.

Without attempting to trace the circuits in detail, an outline of the operation of a successful call w1ll first be given. The application of ringing current tothe trunk at thecentral office causes the operation of relay 110, in turn operating relays 130 and 11 i.

Relay 11 1 operates relay 301 and also marks the trunk to the storing'circuitsflRelay 301 operates cut-in relay 521which locks through the winding of relay 512, in turn operating relays 511, 514 and 516. llfith relays 516 and 521 operated relay 811'in the associated However, in

that a call is incoming.

storing circuit is operated. This relay causes switch 800 to hunt for the trunk and closes :a test circuit by way of brush 802 to the winding of relay 816. Relay 816 in turn operates relays 817, 818,810 and 819thus indicating to the start circuit that a call is waiting by Ground connected to conductors 820 and 821 causes the operation 01" relays 910 and 1010. lVith the operator at her position and idle, so that ground is connected to conductors 226 and 227 relays 914 and 1014 are operated, in turn operating relays 915 and 1015. The operation of these relays advances switch 900 or 1000, depending on which isin service, and relay 913 or 1013 tests whether the next storing circuit still has a call stored on it. If so, relay 913 or 1013 operates, stopping the switch, and ground is connected through relay 916 or 1016 to conductor 823 and thence to conductor 119 andthe winding of relay 124 as an indication to the trunk that it may huntfor an idle receiving circuit. Such a circuit is indicated by battery connected to the terminal of brush 103 or 106 or the corresponding brushes of switches 150 and 160.

Relay 124 connects ground to the lower winding of relay 131 and the corresponding relays associated With switches 150 and 160. Assuming that the distribution control switch 1100 is in position 1 relays 1110 and 1111 will be operated and the circuit of relay 131 completed to battery. Therefore, switch. 100 hunts.v Whenthe position is found switch 100 is brought to rest, extending the talking conductors'to the attendants telephone, after she has been warned by two short tones t is apparent from the foregoing that the direct operation involved in allottinga call to an'idle operator is comparatively simple although the apparatus involved is somewhat intricate. A more detailed discussion of the circuitwill now be given;

Assuinin; the. the subscriber at substation t .111 wishes to give an-order to the department store at which the order tu ret is lo cated, she will give the irectory namber of the order turret to the operator who answers her call. When the connection has been established with an idle trunk outgoingto the orderturret, ringing current will be applied to the trunk, opera ing relay 110 over a circuit which may be traced from the tip of cord 1'32,"ti.p ofjack.133,:outerupper hack contact of relay 134, inner'upper back contact of relay 135, through the winding of relay 110, condenser 123, inner low-er hack c'ontactfor'lrelay 135 lower backco'ntact. of u 7 rela 134 rin of iack 133 tothe rin or" .7 7 r1 a h operated although relay 110 is intermittently operated under the control of the ringing contacts of relay 116 to conductor 119 to mark the trunk as calling to the storing circuits.

Relay 301 in operating closes a circuit from ground at the lower back contact of relay 700, conductor 340, inner lower contact of relay 30 1, contact 321 of transfer key 300,

upper back contact of relay 331, upper back Contact 01 relay 531, lower winding of relay 521, conductor 550, outer upper contact of relay 611, inner upper contact of relay 511 to battery. Relay 521 operates in this circuit and locks in a circuit which extends from ground to the contact of relay 331 as ahove traced and thence through the upper-winding and inner upper contact of relay 521, conductor 551, lower contact of relay 612 to battery through the winding of relay 512.

and resistance 513 in parallel. Relay 512 operates, connecting round from conductor 340 through resistance 518 to the inner upper contact of relay 511, shunting the operating winding of relay 521 and any othercut-in relay which may be operated at this time. It also closes a circuit over its two upper contacts for relay 511 and at its lower con tact shunts the winding of relay 612 and removes battery from the locking circuit of relays 621 to 626. I

Relay 511 in operating opens the operating circuit for the cut-in relays of both allotters'A and B. It also prepares two circuits, one of which tests to determine whether the allotter switches 500 and 600 are in synchronism, that is, are engaging the same storing circuit and the other of which serves to bring switch 500 into synchronism with switch 600. The first circuit may he traced from battery through the winding of relay .514, inner lower contact of relay 610, lower back contact or? relay 611, brush 606 and the terminal on which it is standing, which is cross-connected to the corresponding terminal of brush 506, and thence over hrush 506, lower front contact of relay 511 to ground. If brushes 506 and 606 are standing on corresponding terminals relay 514 operates and the second circuit is ineffective. If this is not the case, the circuit closed by relay 511 over its inner-most lower contact, outer back contact of relay 510, back contact of relay 514, winding of relay 515 to battery iscompleted. Relay 515 in operating extends its I ample, the group served by relay 404, the circuit of relay 720 will extend over conductor operating ground over the back contact of 507 which operates, opening the circuit of relay 508. Relay 508 releases, in turn releasing magnet 507 and stepping the brushes of allotter switch 500 to the next storing circuit. This reciprocal action continues until brush 506 engages the terminal corresponding to that engaged by brush 606 or until the timing relays function. If the call were incoming over a trunk belonging to a group served normally by the B allotter, switch 600 would be brought into synchronism with I switch 500 in a corresponding manner.

Assuming that the switches are synchronism and that relay 514 operates, circuit is closed from ground over the innermost lower contact of relay 511, outer lower contact of relay 510, front contact of relay 514,

winding of relay 516 to battery. 7

When relay 301 operated it closed a circuit from battery through the winding of relay 5 720 conductor 721, outerupper front contact of relay 301, lower back contact of relay 542, lower back contact of relay 531, assuming that this is the first call in this group, to ground.

The operation of relay 521 closes a circuit from ground at the inner lower contact of relay 517, lower winding of relay 552, outer v upper'front contact of relay 521 through the upper winding of relay 531' to battery. Re-

lay 552 operates'but relay 531 cannot, due

to the high resistance of the winding of relay 552. lVith relay 552 operated a circuit is closed from battery at the lower front contact of relay 720, winding of relay 722, conductor 723, contact of relay 552 to ground. Relay F 722 connects battery and ground to the winding of relay 724 which in turn connects battery over its contacts to the lower windings of relays 531 to 536 and 631 to 636 inclusive.

When relay 516 operates it connects the up per low resistance winding in parallel with the lower high resistance winding of relay 552 and relay 531 operates, connecting ground over its lower armature to its lower winding, remaining operated-and locked as long as relay'7 20 remains operated. The circuit of relay 720 extends over the front contacts of operated group relays and the'back contacts of the corresponding lock-out relays. Therefore, if the call in the group served by relay 301 is the only one awaiting attention atthis time the operation of; relay 531 will open the circuit of relay 720 and relay 531 will release following the release of relays 301 and 521. If a call is waiting in another group, for es:-

721, outer upper contact of relay 404, upper back contact of relay 641, lower back contact of relay 634-to ground and relay 531' held {operated until after this second call has been operating relay 814 Similar closed in the B allotter;

served. A second call during this period in the group served by relay 301 would not be effective to hold relay 720 operated after the release of relay 404 since the operated contact of relay 531 holds open the circuit of relay 7 20. 1 I I -Relay 516 also closes circuit from ground "over the inner upper contact of relay 517,

upper contact of relay 516 to the lower armatures of' the cut-in relays. With relay 521 operated this ground extends over the lower front contact of thatrelay, brush 504, conductor 831, inner lower contact'of relay 810, winding of relay 811 and battery, thus initiating the operation of the storing circuit. The operation of relay 811 causes the operation of switch800 to hunt for the trunk marked by ground over conductor 119 and determines that brushes 801 and 802 will be'used to connect thestoring circuit with the trunk circuit. Relays 521 to 526 identify the group to which the incoming trunk belongs to the storing circuit by connecting ground to one of the con 'ductors 831 o 833 either alone or in'combination'with conductor 834, thus operating one of the relays 811 to 813 and operating or not circuits are The circuit for operating switch 800 may be traced from battery through-the winding of relay 815 over the back-contacts of magnets 807 and 857. outer upper contact of relay 810, back contact of relay 816 to ground at the outer lower contact of relay 811. Relay 815 closes a circuit from ground over the back contact of relay 817, contact of relay 815, upper normal contact of relay 814, winding of magnet 807 to battery. Relay 815 and magnet 807 cooperate to advance switch 800 in search of the trunk marked. When this-trunk is found the around connected to conduct-or 119 is extended over brush 802. middle lower contact of relay 811, lower back contact of relay 814. outer upper back contact ofrelay 819. winding of relay 816 to batter Relay 816 in operating disconnects around from relay 815 and connects it to the upper winding of relay 817 and battery. Relay 817 in operating closes a' circuit from around over its upner front contact to the winding of relay 818. It also closes a circuit over its lower front contact to lock relay 811. Relay 818 in operating closes an obvious circuit for relays810'and 819. Relays 818 and, 819 control circuits for indicating "to the si nal circuit that a callhas been 1 per contact of rela'y811 to brush-801, con- 301 permitting that relay to release. It also disconnects ground from conductor 119 but relay 817 is already held operated and is therefore unaffected by the release of relay 816. In addition relay 116 also prepares a I circuit from battery through the winding of relay 124, upper front contact of relay 116 to conductor 119. The trunk circuit now awaits the action of the start circuit.

Relay 810 in operating opens the circuit of relay 815 to prevent switch 800 from moving out of engagement with the trunk of Fig. 1. It also disconnects the control conductors 831 to 834 from relays 811 to 814. Relay 819 connects ground over its outer lower contact to conductor 825, brush 505, lower back contacts of relays 517 and 515 back contact of magnet 507, upper back con tact of relay 515 to the winding of relay 700. This circuit also extends in parallel from conductor 825 over brush 605, middle lower back contact of relay 617, lower back contact of relay 615, back contact of magnet 607, upper back contact of relay 615, to the winding of relay 700. Relay 700 in operating disconnects ground from conductor 340 thus releasing cut-in relay 521 and in turn the lock-out relay 531 unless another call is waiting. Relay 700 also closes a circuit over its outer lower front contact,'1niddle upper contact of relay 517, to the winding of the magnet 507 and battery and a second circuit over its inner lower front contact, upper back contact of relay 617 to the winding of magnet 607 and battery. These two magnets operate and when both are operated open the circuit of relay 700 which releases in turn releasing the magnets and advancing the allotter switches to preallot the next storing circuit. I

Relay 818 in addition to the functions above described connects ground over its inner con tacts to conductors 820, 821 and 822 leading to the start circuit. The connection of ground to conductors 820 and 821 completes circuits'for relays 910 and 1010 which both operate. As soon as relay 910 operates it closes a circuit from battery through the winding of relay 908, back contact of magnet 907 back contact of relay 913, brush 902 and its strappedoif-normal terminals, inner lower back contact of relay 912, right normal contact of key 911 to ground at the outer upper contact of relay 910. Relay 1010 attempts to prepare a similar circuit for relay 1008 but it will be remembered that only one of the switches 900 and 1000 functions at a time audit is assumed that switch 900 is the one now in use. The circuit closed by relay 910 is therefore effective while the attempted closure by relay 1010 is ineffective, since brush 1002 is engaging the twenty-second terminal which is disconnected. Relay 908 in operating closes a circuit for magnet 907 which opens the circuit of relay 908 and thereby the circuit of magnet 907, and advances the sta t circuit to the next storing circuit. A cir it is then closed from battery through the winding of relay 913. outer lower back contact of relay 912, brush 901 to conductor which is grounded on the operation of r 818. Relay 913 operates, opening the circuit of relay 908 and preventing the further advan m of switch 900.

Relay 910 also prepares a circuit from battery through the winding of relay 914, outer upper back contact of relay 940, outer lower contact of relay 910 to conductor 226 which terminates in ground at an operators position, if that operator is idle.

Referring for the moment to the circuit of 2, it will be seen that the connection of headset 220 to the telephone circuit completes a circuit from ground through the contacts of jack 22 2 and plug 221 and the operators transmitter to battery through the winding of relay 224. Relay 224 closes a circuit from ground over its outer left contact, right back contact of relay 202, outer lower normal contact of key 201, lower normal contact of key 209, inner lower normal contact of key 240, lower normal contact of key 241, winding of relay 203 to battery. Relay 203 in operating connects ground over its middle left contact to conductors 226 and 227. It also connects battery through relay 245 and resistance 246 in parallel, outer right contact of relay 203, normal contact of key 244, inner upper normal contact of key 201 to conductor 213 to mark the receiving circuit idle to the trunk circuits. In addition, relay 203 connects ground from the inner left contact of relay 224, over the outer left and inner right contacts of relay 203, to conductor 251 to mark the position idle to the distribution control circuit. Key 201 is a release key and key 209 is a holding key. Keys 240 and 241 connect the desk with a trunk outgoing to the central office or to the associated P. B. X. relay 202, as will be shown hereinafter, is operated during the time that the incoming trunk is connected with the receiving circult. Therefore, it is apparent that the operation of any one of the keys or the association of a trunk with a receiving circuit prevents the desk from being marked idle to the start circuit, the trunk circuits or the distributing circuit.

The circuit of relay 914 extends in multiple to all desks so that as long as one operator is idle the circuit will be completed whenever relay 910 operates. Relay 914 also closes an obvious circuit for relay 915. Relay 1010 closes a similar circuit for relay 1014 to conductor 227 which also operates if an operator available and closes an obvious circuit for relay 1015'. elay 911 also closes .a parallel circuitforrelay 1015 and relay 101 1 closes a parallel circuit for relay 915, thus securing V I the operation of these two role s even. though one of the relays 910, 914:, 1010 or 10141 fails to operate.

'The operation of relay 913 as above described closes a circuit from battery through the winding of relay 918, back contact of relay 919, inner upper front contact of relay 915, front contact of relay 913, brush 902, back contact of relay 912, right norinal contact of lrey 911 to ground at the up erinost contact of relay 910. irelay 918 initiates a timing operation for the purpose of determining whether the start circuit functions properly. The operation of the t ming relays is fully described in the above id tilled patent to Carpenter et al.

7 At the time relay 914 oper s, it closes a circuit from ground at the inner upper back contact of relay 940, through the winding; of relay 916, inner lower contact of relay I 91 1, lower baclr contact of relay 91'1", brush 906, conductor 823, upper front contact of relay 819, lower back contact of relay 81 1, middle lower contact of relay 811, brush 802, conductor 119, upper front contact of relay 116, winding of relay 124; to battery as an indication to the trunk that it may hunt for an idle operators position. This same circuit is also closed 'at the lower contact of relay1014 and a similar circuit is'prepared by both relays 101 1 and 914 tojbrush 1006 'which is ineffective because of theposition switch 1000. The presence of relay 916 in this circuit reduces the potential on the terminal of brush 802 through which the circuit passes so'that it will not interfere with the'operation of storing circuit switches hunting over terminals inultipled thereto in Search of other trunks. Relay 916 in'closing its frontycontact renders this 'circuit independent of the contacts of relays 911 and Relay 124 in operating prepares an operating circuit for relay 131. This circuit may be traced from ground over the inner lower and upper back contacts of relay back contact of relay 1 10, middle upper frontfor these three relays extending from ound over its inner lower front 0011:2265 through the winding of relay 14-0 in parallel to the locking arinaturcs of relay 131 and the corresponding relays of switches 150 and 160. In addition relay 124 prepares a test circuit tact through the windin of relay 125, 'loi" front contact of relay 116 to the middle upper.

front contact of relay 131'and'in parallel to corresponding contacts of the relays associated with the other two switches. \Vhich of the three .switches'is to be employed, and in consequence which .of the three groups of order desks is to be hunted over, is determined by the distribution control circuit of grounded, operating relay 1110. With relay 1110 operated, battery is connected over the front contact of relay 1111, upper front contact of relay 1110 to conductor 1114cand the lower winding of relay 131.

Therefore, when relay 12 1 operates connecting ground to'the lower winding of relay 131, that relay operates to cause the operation of switch 100. Relay 131 looks to battery over its middle lower contact, upper winding and inner upper contact, winding of relay 1 10 to ground at the inner lower contact of relay 12 1. Relay 1 10 in operating closes a circuit from ground at the upper back contact of'relay 125, lower front contact of relay 1 10, back contact of magnet 107 and thence over the back contacts of the corresponding magnet-s of switches 150 and160 to the winding of relay 108 and battery. Relay also disconnects ground from the contacts of relay 12stto prevent the operation of either of the relays'corresponding to relay1'31 in the other two switches. Relay 108 in operating closes a circuit from ground over its front contact, inner lower contact of relay 131 to the winding of mag et 107. Parallel circuits extend to the inner lower contacts of the relays corresponding to relay 131, but since these relays are not operated, switches and remain at rest. Magnet 10'? in operating opens the circuit of relay 108 which releases in turn releasing magnet 10?, whereupon, the circuit of relay 108 is reclosed, and the relay and magnet operate and release in turn to advance switch 100 in search of an idle receiying circuit as indicated by the connection of battery to conductor 213 as above described. 5

When such a receiving circuit is found, a circuit-is closed from battery over conductor 213, brush 103, middle upper contact of relay 131, lower front contact of relay 116, winding of relay 125 to ground at the outer lower contact of relay 12 1. Relay 125 in operating opens the circuit of relay 140, in turn round from releasin clay 108, and magnet 107, bringing r Relay 125 closes a circuit front contac winding 141 connects uctors from the repeat- .,l 112- through the front contacts of rereceiving circuit and through the windings of relay 208 and the winding of relay 207.

111 addition relay 141 disconnects ground 203 and that r uting circuits.

from contacts of relay 124, opening the energizing circuit of relay 131, but connects it to the locking circuit of relay 131, holding that relay operated. Relay 206 in the receiving circuit operates, closing obvious circuit for relay 202 which looks over its inner left contact and the inner lower normal contact of lrey 201 to the @1161 left front contact of relay 224. Belay 202 opens the circuit of relay lay releases, removino the idle indication from the start-,trunh and distrib- Relay 202 also connects ground over the inner lower back contact of relay 208 to the winding of relay 242 which connects ground to i terrupter 243 and the primary circuit of coil In addiiton it connects ground lamp 252, lighting that lamp as a busy signal.

The connection of relay 206 and 207 across the tip and ring conductors causes the operation of relays 142 and 143 in the trunk circuit. Relay 142 in turn operates relay 144 which 1n turn operates relay 115. Relay 115 in operating connects resistance 146 across the tip and ring conductors. thus closing a direct current path which the tripping'relay of the cord circuit can operate to disconnect ringing current from the trunk. .Relay 115 also opens the circuit of relay 116 and. the locking circuit of relay 130 which releases in turn releasing relay 114. lVith relay 114 released, the resistance 146 is removed from across the tip and ring conductors. A circuit is also closed from battery, through the winding of relay 135, back contact of relay 114, to ground at the lower front contact of relay 144, or the inner upper front contact of relay 115. With relay 115 operated, the incoming tip and ring conductors are con nected together through the windings of the repeating coil 112, front contact ofrelay 143 and resistance 147. A signal is thereby transmitted back to the calling ofiice for supervisory purposes.

The operation of relay 135 reverses the connection of battery and ground through the right windings of repeating coil 112 to the winding of polarized relay 207 so that relay 207 now operates. Relay 207 in operat" ing closes a circuit from battery through the winding of relay 228, front contact of relay 207, inner upper back contact of relay 208., to ground at the right front contact of relay 202. Relay closes a circuit through the secondary winding of tone coil 229 over its and ring conductors of the right contact, outer lower back contact of relay 208, inner-upper normal contact of key 209, outer lower normal. contact of key 240 throughthe repeating coil 223, upper normal contact of key 240, outer upper normal c0ntact of rey 200, outer upper back contact of relay 208, normal contact of relay 230 to ground at the inner left contact of relay 228. A tone is therefore transmitted to the operator. Relay 228 also closes an obvious circuit for relay which is slow to operate, and after an interval opens its normal contact, and disconnects the tone from the operators receiver. Relay 230 also closes a circuit for hich is also slow to operate and after another interval recompletes the secondary circuit ofthe tone coil over the normal contact of relay 232, left contact of relay 231, alternate contact of relay 230 to ground at the inner left contact of relay 228. Relay 231 also operates relay 232 which, after an interval, measured by its slow-to-operate character, again opens the tone circuit completing the second of the socalled zip tones. It also extends the circuit closed from ground at the inner left contact of relay 228 over the contact of relay to the winding of relay 208. If key 235 is operated it likewise operates peg count meter 234 and relay Relay 208 opens the circuit of relays 228 and 242 and closes a locking circuit for itself over its alternate contact to ground at the inner ri ht contact of relay 202. It likewise extends the trunk conductors to the headset 220. The order clerk or operator may now talk with the customer and record the order.

The disconnection of relay 116 from conductor 120 opens the circuit of relay 817 in the storing circuit. Relay 817 in releasing opens the circuit of relay 818 in turn releasing relays 810 and 819. Relay 817 also opens the locking circuit of relay 811 and the storing circuit is restored to normal. The release of relays 817 and 818 opens the circuits of relays 913, 910 and 1010 which in turn release the remaining: relays of the start circuit, the switch 000 remaining in the same position until the reception of a. call causes it to advance to start another trunk.

If other calls are stored d waiting, relays 910 and 1010 remain operated, but the release of relay 913 permits the advance of switch 900 to the next storing circuit. When an operator becomes idle relay 914 operates to transmit the starting signal to the trunk.

It will be ren'iemhered that battery was ferates in this circuit.

of relay 203. Relay. 245 connects ground over its inner left contact to conductor 24?. If there are idle receiving circuits in the second and third groups of desks, relays 1122 and 1132 will be operated over circuits similar to that previously traced over conductor 251.- The connection of ground to conductor 247 therefore closes a circuit over the upper front contact of relay 1132 and over the inner lower contact of relay 1122 to the winding of relay 1115. With relay 1110 operated as above described, relay 1116 is also operated and a circuit is closed from ground over thecontacts of relays 1116 and 1115 to the winding of magnet 1104; Magnet 1104' op- When relay 116 releases, the circuit of relays 125 and 245 is opened and relays 245 and 1115 release, in

- to again preallot Group 1.

l contact of relay 1123 will be connected to the turn releasing magnet 1104 and advancing switch 1100 to its next position. The ad .vance of switch 1100 opens the circuit of relay 1110 which releases, in turn releasing relay 1116 and opening the operating circuit of magnet 1104. With brush 1102 in position 2, and relay 1123 operated from relay 1122, relays 1121', 1120 and 1126 are operated in turn. A circuit is now prepared from battery over the contact of relay 1121, upper contact of relay 1120 to conductor 1124 which extends in parallel to the relays correspond ing to relay 131 associated with the second switch of each trunk, which corresponds to switch 150. Similarly when a receiving circuit of the second group has been taken for use relay 1125 is operated from the receiving circuit, if there are idle operators in Groups 1 or 3 and together with'relay 1126 advances the switch 1100 to position 3. The third group of desks is allotted in position 3 and following the selection of a receiving circuit in the third group switch 1100 is advanced If no attendants are idle in two of the three groups, for example, in Groups 2 and 3, the connection of ground to conductor 247 is inefiective and v Group 1 continuesv to be used alone.

If there should be no desks available in Group 2 (following the selection of a desk in Group 1) but idle desks exist in Group 3, ground over the front contact of relay 1133 and the back Group 2 terminals of brush 1103 to advance the switch to allot Group 3.

If, after talking with the customer, the operator at the order desk finds it necessary to have the assistance of a salesman in determiningthe details of an order or finds that the calling party really wishes to speak with a particular person served by a line appearingat the house private branch exchange, the order clerk may operate key 244 connecting ground through resistance 248 to battery through resistance 250 and then connecting up conductor 213 to a point between the two resistances. Following the release of relay 116 suiiicient to operate relay but insultiof the operators cord circuit, sleeve of jack 170, contact 171, winding of relay 148 to battery. Relay 148 connects ground over its lower contact to the winding of relay 134 and battery. Relay 148 also closes at its upper front contact a shunt around the front contact of relay 143. Relay 134 extinguishes lamp 172 and connects the tip and ring of jack to the tip and ring of the trunk so that the branch exchange operator may converse with the calling subscriber and the order operator and extend the branch con nection to any person desired. If the con nection to the branch exchange was merely for assistance, when the consultation is completed the branch exchange line releases and the branch operator removes her cord circuit releasing relays 148' and 134. The restoration of key 244 releases relay 145 and the re mainder of the order may be completed.

\Vhen the conversation is completed the release by the calling subscriber is ineffective on the trunk circuit. The operator in order to release, operates key 201 thereby closing a circuit from battery over the normal contact of key 210, winding of relay 249, upper operated contact of key'201 to ground at the in ner right contact of relay 202. Belay 249 in operating disconnects the tip conductor from the operators telephone. It also connects ground over its front contact through the left winding of relay 206 to the tip conductor and through the winding of relay 207 and the right winding o1 relay 206 to the ring conductor. Relay 143 is held operated in this circuit but relay 142 is shunted and released. Relay 142 in releasing, releases relay 144 which in turn releases relay 115 and relay 135. The release of relays115 and 144 releases relay 141 and disconnects relay 143 from the receiving circuit thereby releasing relay 143. The release of relay 143 opens the direct current circuit over the tip and ring conductors to the central office and there by transmits a release signal to the central oflice operator. If the central oflice is a dial office, the release of relay 143 initiates the automatic release of the switching apparatus.

cuit from the receiving circuit. It is to be noted that, if a connection has been established to a telephone connected to the private branch exchange, relays 148 and 134 are operated to connect the calling subscriber to the branch exchange switchboard. The release of the receiving circuit from the trunk circuit by the operation of key 210 does not in any way afiect the branch connection, and the operator can free her desk to answer other calls during the time that the calling subscriber is engaged with the branch exchange.

The operation of key 201 opens the looking circuit of relay 202, whilethe release of relay 141 opens the operating. circuit of relay 202. Relay 202, therefore, releases, extinguishing lamp 252 and lighting lamp 253.

Key 201 also opens the circuits of relays 203 and 245 to prevent marking the desk idle with the release key operated. When the key is restored, relay 203 operates, and again pre- Qconnect battery over the outer operated conpares the circuit of relay 245.

The order operator can signal the central ofiice operator by operation of key210,wh1ch closes a circuit from battery over theinner operated contact of key 210 to the winding of relay 205, outer upper normal contact of key 201 to ground at the right front contact of relay Key 210 and relay 205 jointly tact of key 210, inner contact of relay 205 through the right winding of relay 200 to the ring conductor and through the winding of relay 207, and the left winding of relay 206 to the tip conductor, thus holding relay 142 operated and shunting relay 143, which 4 opens the supervisory circuit, signaling the operator at the central oflice in synchronism with the operation of key 210.

It will be noted that if, following the finding of a clerks position the tip and ring conductors are not properly connected through, for example because of poor contact at the switch, relay 142 cannot operate and in turn cannot operate relay 115 so that relay 116 does not release to free the storing circuit. The timing relays of the start circuit will advance the start circuit to the next storing 01rcuit in the manner described in the 'above identified Carpenter patent. After all intermediate calls have been extended to the order desks the start circuit will again associate itself with the storing circuit attached to the trunk previously connected to, and another attempt will be made to connect with the order desk. p

The relays 730 to 738 inclusive of Fig. 7 constitute a relay interrupter for supplying interrupted ground to the allotter and the start circuit. Relay 730 is operated as soon as either relay 1014 or 914 operates in the i start circuit as shown. Two other circuits for operating this relay are also provided but winding of relay 731, and the other through condenser 739, resistance 740, outer upper contact of relay 730, and the upper winding of relay 7 31, to junction point 743 and over the upper back contact of relay 732 through resistance 741 to battery. The windings of relay 7 31 are so arranged that the charging current through the upper winding opposes and delays the effect of the steady current through the lower winding. When a steady state is reached relay 731 operates. The operation of relay 731 closes a circuit from ground over the inner contact of relay 730, contact of relay 7 31, winding of relay 732 to battery. The operation of relay 732 transfers battery through resistance 741 from the junction points 743 to point 748 and transfers ground from the unction 748 to junction 743 thus reversing the current flow throughthe windings of relay 731. Condenser 739 is now discharged and charged in the opposite direction. hen the current flow for charging condenser 739 ceases, relay 7 31 is energized in such a direction as to cause it to open its contact and relay 732 releases. With relay 7 32 released, the two circuits initially traced through the windings of relay 731 are restored and the relay recloses its contact, again operating relay 732. Thus relays 731 and 732 are intermittently operated as long as relay 730 continues to hold their circuits closed. Each time that relay 732 operates itconnects ground from the front contact of relay 730 over its middle upper front contact to conductor 744 and over its outer upper front contact to conductors 7 45 and 746. The connection of ground to conductor 745 controls The connection relay 7 36 in turn operates and releases relays 737 and 738. From the time that relay 730 operates until relay 736 is operated, ground is connected ,over the inner contact of relay 730, lower back contact of relay 736, lower back contact of relay 737, to conductor 747' which extends to the allotter alarm circuit and the signal circuit to control the timing relays in those circuits in place of the me chanical interrupters shown in the Carpenter 

